@index is not calculated correctly when there are identical elements in the list

[retro]

Passing list that looks like:

var data = new can.List(['foo', 'bar', 'baz', 'qux', 'foo'])

will break @index calculation. Instead of : 0 1 2 3 4 it will produce 0 1 2 3 0

[imjoshdean]

+1

In hindsight this makes sense, I didn't think about this use case at the time.